uart0_stdio1.c

c8051f020开发板的所有参考程序

//-----------------------------------------------------------------------------
// UART0_Stdio1.c
//-----------------------------------------------------------------------------
// Copyright 2001 Cygnal Integrated Products, Inc.
//
// AUTH: BW
// DATE: 18 AUG 01
//
// This program configures UART0 to operate in polled mode, suitable for use
// with the <stdio> functions printf() and scanf(), to which examples are
// provided.  Assumes an 22.1184MHz crystal is attached between XTAL1 and 
// XTAL2.
// 
// The system clock frequency is stored in a global constant SYSCLK.  The
// target UART baud rate is stored in a global constant BAUDRATE.
//
// Target: C8051F02x
// Tool chain: KEIL C51 6.03 / KEIL EVAL C51
//

//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include <c8051f020.h>                 // SFR declarations
#include <stdio.h>

//-----------------------------------------------------------------------------
// 16-bit SFR Definitions for 'F02x
//-----------------------------------------------------------------------------

sfr16 DP       = 0x82;                 // data pointer
sfr16 TMR3RL   = 0x92;                 // Timer3 reload value
sfr16 TMR3     = 0x94;                 // Timer3 counter
sfr16 ADC0     = 0xbe;                 // ADC0 data
sfr16 ADC0GT   = 0xc4;                 // ADC0 greater than window
sfr16 ADC0LT   = 0xc6;                 // ADC0 less than window
sfr16 RCAP2    = 0xca;                 // Timer2 capture/reload
sfr16 T2       = 0xcc;                 // Timer2
sfr16 RCAP4    = 0xe4;                 // Timer4 capture/reload
sfr16 T4       = 0xf4;                 // Timer4
sfr16 DAC0     = 0xd2;                 // DAC0 data
sfr16 DAC1     = 0xd5;                 // DAC1 data

//-----------------------------------------------------------------------------
// Global CONSTANTS
//-----------------------------------------------------------------------------

#define SYSCLK       22118400          // SYSCLK frequency in Hz
#define BAUDRATE     115200            // Baud rate of UART in bps

sbit LED = P1^6;                       // LED = 1 means ON

//-----------------------------------------------------------------------------
// Function PROTOTYPES
//-----------------------------------------------------------------------------

void SYSCLK_Init (void);
void PORT_Init (void);
void UART0_Init (void);

//-----------------------------------------------------------------------------
// Global VARIABLES
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// MAIN Routine
//-----------------------------------------------------------------------------

void main (void) {
   char input_char;

   WDTCN = 0xde;                       // disable watchdog timer
   WDTCN = 0xad;

   SYSCLK_Init ();                     // initialize oscillator
   PORT_Init ();                       // initialize crossbar and GPIO
   UART0_Init ();                      // initialize UART0

   // transmit example

   printf ("Howdy!\n");

   // receive example: a '1' turns LED on; a '0' turns LED off.

   while (1) {
      input_char = getchar();
      printf (" '%c', 0x%02x\n", (unsigned char) input_char, (unsigned) input_char);
      switch (input_char) {
         case '0':
            LED = 0;
            break;
         case '1':
            LED = 1;
            break;
         default:
            break;
      }
   }
}

//-----------------------------------------------------------------------------
// Initialization Subroutines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// This routine initializes the system clock to use an 22.1184MHz crystal
// as its clock source.
//
void SYSCLK_Init (void)
{
   int i;                              // delay counter

   OSCXCN = 0x67;                      // start external oscillator with
                                       // 22.1184MHz crystal

   for (i=0; i < 256; i++) ;           // wait for oscillator to start

   while (!(OSCXCN & 0x80)) ;          // Wait for crystal osc. to settle

   OSCICN = 0x88;                      // select external oscillator as SYSCLK
                                       // source and enable missing clock
                                       // detector
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports
//
void PORT_Init (void)
{
   XBR0    |= 0x04;                    // Enable UART0
   XBR2    |= 0x40;                    // Enable crossbar and weak pull-ups
   P0MDOUT |= 0x01;                    // enable TX0 as a push-pull output
   P1MDOUT |= 0x40;                    // enable LED as push-pull output
}

//-----------------------------------------------------------------------------
// UART0_Init
//-----------------------------------------------------------------------------
//
// Configure the UART0 using Timer1, for <baudrate> and 8-N-1.
//
void UART0_Init (void)
{
   SCON0  = 0x50;                      // SCON0: mode 1, 8-bit UART, enable RX
   TMOD   = 0x20;                      // TMOD: timer 1, mode 2, 8-bit reload
   TH1    = -(SYSCLK/BAUDRATE/16);     // set Timer1 reload value for baudrate
   TR1    = 1;                         // start Timer1
   CKCON |= 0x10;                      // Timer1 uses SYSCLK as time base
   PCON  |= 0x80;                      // SMOD00 = 1 (disable baud rate 
                                       // divide-by-two)
   TI0    = 1;                         // Indicate TX0 ready
}